Compressed wood product and manufacture

ABSTRACT

The invention described is a method for compressing wood products in a manner which achieves fixation of compression deformation. The method includes two compression stages. In between those stages the wood is coated and impregnated with a fatty acid. The wood, after the second compression step is annealed to set the compressor. The product may be used for flooring, panelling and for making wooden articles.

TECHNICAL FIELD

This invention relates to manufacturing a compressed wood product. Moreparticularly it relates to a process for manufacturing a compressed woodproduct where the compression of wood fibres is permanently fixed.

BACKGROUND ART

It is known in the art that both softwood and hardwood can be compressedinto densified and hardened products. There are many ways of achievingthis including the use of heat, steam, pressure and chemicals includingadhesives. The objective of a process of wood deformation is to achieveboth densification of the wood and permanent fixation of thedensification in the product in a manner which is efficient and hasminimal effect on the environment.

A discussion of possible ways in which to achieve permanent fixation ofcompression deformation of soft wood is found in Inoue (see reference).The author of that paper suggested that three methods to permanently fixthe compression deformation of wood. The first was to make woodinaccessible to water using acetyl groups. The second was to formcross-linking between wood components using para-formaldehyde. The thirdwas to release elastic energy stored by deformation by dippingcompressed wood in acidic acid and hydrochloric acid.

In U.S. Pat. No. 3,981,338 there is described a method of compressingdebarked and dried logs in a mould where they were immersed with aliquid adhesive. The logs were compressed in the mould to a thicknesssmaller than that finally required. They were then allowed to expandwhile still immersed in the adhesive and compressed to the final desiredthickness and subjected to an elevated temperature to allow the adhesiveto harden.

In U.S. Pat. No. 4,606,388 there is described a method of compressinglow density woods. A wood member in a green state is subjected toammonia to plasticise it to a sponge-like form. It is then subjected toa series of compression cycles and dried.

In published Japanese application Nos. JP 10-217210; JP 11-114915; andJP 11-320510 there are described methods of forming pressed wood usinghigh pressure compressing devices.

In U.S. Pat. No. 5,343,913 there is described a method of compressingwood involving softening the wood at high temperature and high watervapour temperature and then compression moulding the wood to reduce itto one half to one third of its original thickness. The compression isfixed by maintaining wood in a compressed stated for a predeterminedperiod of time.

It is an object of this invention to provide a method of manufacturingdensified wood with permanent fixation which is an alternative to theabove described methods or at least to offer the public a useful choice.

DISCLOSURE OF INVENTION

Accordingly the invention may be said broadly to consist in a method offorming a compressed wood product comprising the steps of:

subjecting a piece or pieces of softwood, with a moisture content ofapproximately 30-40% (w/w) to a first heated compression step in whichthe density of the softwood is increased to a first predetermined leveland the moisture content is reduced to between approximately 3-8% (w/w),

releasing said wood from said first compression step, coating andimpregnating said compressed wood with a fatty acid,

subjecting said impregnated compressed wood to a second heatedcompression step in which the density of said compressed wood isincreased to a second predetermined level and the moisture content isfurther reduced and in which said fatty acid is further impregnated intosaid compressed wood, and

releasing said wood from said second compression step and allowing saidimpregnated compressed wood to anneal while cooling to ambienttemperature.

In another embodiment, the invention may be said broadly to consist in amethod of forming a compressed wood product comprising the steps of:

subjecting a piece or pieces of diffuse porous hardwood, with a moisturecontent of approximately 40-50% (w/w) to a first heated compression stepin which the density of the hardwood is increased to a firstpredetermined level and the moisture content is reduced to approximately4-8% (w/w),

releasing said wood from said first compression step and coating andimpregnating said compressed wood with a fatty acid,

optionally, when said wood is hardwood, subjecting said impregnatedcompressed wood to a second heated compression step in which the densityof said compressed wood is increased to a second predetermined level andthe moisture content is reduced to suit end product requirements, at aslow as 2-4% (w/w) and in which said fatty acid is further impregnatedinto said compressed wood, and

releasing said wood from said second compression step and allowing saidimpregnated compressed wood to anneal while cooling to ambienttemperature.

Preferably when said wood product is softwood, said softwood issubjected to a preliminary drying step prior to said first compressionstep.

Preferably when said wood product is hardwood, said hardwood issubjected to a preliminary drying step prior to said first compressionstep.

Preferably said preliminary drying step is a pressure drying step.

Preferably said first compression step is maintained for a time periodof up to five minutes.

Preferably said first compression step is conducted at a pressure offrom 50 to 114 kg/cm² according to wood species.

Preferably the temperature of said first compression step is within therange of 140° C. to 185° C.

In one alternative when said wood is softwood it maybe subjected tosteam heat or any other heat at a temperature up to 200° C. prior tosaid first compression step.

Preferably said compressed wood is impregnated by passing it through aheated bath only, or in combination in vacuum pressure chamber.

Preferably said bath or pressure tank is heated to a temperature of fromabout 60° C. to 120° C.

Preferably said fatty acid is in a non-aqueous carrier.

Preferably said non-aqueous carrier is paraffin.

In one alternative said fatty acid is stearic acid.

In another embodiment said fatty acid is palmitic acid.

In another alternative the fatty acid is a mixture of palmitic andstearic acid.

Preferably said second compression step is conducted at a temperaturebetween 60° C. and 140° C.

Preferably said second compression step is conducted for from 3 to 6minutes.

Preferably said annealing is assisted by subjecting said compressed woodfrom said second heated compression step to radiation.

Preferably said radiation is infrared radiation.

In one alternative said radiation is microwave radiation.

In a second alternative said radiation is gamma radiation.

Preferably the process includes the preliminary step of cutting a loginto pieces.

In one embodiment said pieces are flitches.

Preferably said flitches are sliced.

In another embodiment said flitches are subjected to infrared radiationprior to being sliced.

In another embodiment a log is cut into side slab wood withpredetermined thicknesses which establish flitch size parameters.

Preferably when a said log is diffuse porous hardwood said flitches orslabs cut therefrom are stored for up to four weeks prior to furthertreatment.

In one alternative, said wood is subjected to a preliminary step ofimmersion in hot water or superheated steam.

Preferably said wood is subjected to a preliminary drying step to reduceits moisture content prior to steam heating and before said firstcompression step.

In one embodiment said drying step is reduced pressure drying.

In one embodiment said compressed wood product after annealing issubjected to a further drying step.

In a further alternative said further drying step is followed by asupplementary packet assembling compression step.

Preferably said assembling compression step is done at ambienttemperature.

In another alternative said compressed wood from the said assemblingcompression step is subjected to further processing.

Preferably said further processing includes laminating compressed piecesof the modified wood together, or with other wood fibre panels.

This invention may also be said broadly to consist in the parts,elements and features referred to or indicated in the specification ofthe application, individually or collectively, and any or allcombinations of any two or more of said parts, elements or features, andwhere specific integers are mentioned herein which have knownequivalents in the art to which this invention relates, such knownequivalents are deemed to be incorporated herein as if individually setforth.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be more fully understood by having reference to theaccompanying drawings in which:

FIG. 1 is a flow diagram schematically outlining the processing steps ofa preferred embodiment.

FIG. 2 is a cross-sectional end view of a debarked log sawn to producepieces of wood to be compressed according to the process of thisinvention.

MODES OF CARRYING OUT THE INVENTION

Log Processing—Wood Preparation

In this specification the expression “moisture content” means the weightof water expressed as a percentage of the dry weight of wood containingthe water.

Referring to FIG. 1, step 1 is the transport of cut logs to the logyard. Step 2 is the selection of the logs. Where the wood chosen ispinus radiata or other softwood species clearwood buttlogs of up toapproximately 5 to 6 metres in length are chosen In another alternative,logs which have long internodel spacing between the branches are chosen.Using log optimisation computer programs it is possible to select cutlengths between knots.

It is also possible to select younger trees where it is intended thatthe knots are processed in accordance with one aspect of the invention.

Step 3 is the debarking of soft wood logs which is carried out in aconventional way well known in the art.

Step 4 is cutting the logs to length. The method of cutting isconventional to saw mills. The lengths chosen are determined by thescanning and optimisation software.

Use of a scanning and optimisation software is shown at Step 5 ofFIG. 1. Selected logs are scanned and optimised by both log end scanningand a three dimensional all round log measuring device to assist in thelog being sawn to specified flitch cutting patterns. This technologyalso provides for cutting useful wood portions out of low grade logs ordefective portions of a log. The log input data can also be related tothe product output volumes. The process is under continuous monitoringso as to optimise production using commercially available softwarepackages to do this.

A first log sawing step 6 can be carried out by the preferred method ofcomputerised log scanning and optimisation to establish the flitchcutting patterns based on the relationship of the softwood core wooddiameter and the slabwood widths to maximise on the wood recovery ofeach log according to product requirements.

FIG. 2 illustrates how flitches are sawn at stations 6, 7, 8A or 8B toprovide for optimised “wider section” slabwood as compared to standardflitch cutting. Wider section flitches may be cut according to variedcutting patterns to produce specific quarter sawn flitch widths, andalso thicknesses of slabwood to suit production schedules.

A log 32 as illustrated in FIG. 2 is subjected to saw cats illustratedby the solid straight lines. The main pieces of slabwood to be quartersawn are produced on the left and right sides and are numbered 40 and41. At the centre of the log is the corewood 36. There are otherflitches 38 (only one of which has a reference numeral) immediatelysurrounding corewood 36.

Slabwood may be cut into smaller pieces such as are illustrated by thesmall corner segments 34 and 35. Also illustrated are small segments ofslabwood such as 40 a, 41 a and 41 b. Small corner pieces such assegments 34 and 35 will be cut to a minimum saw width of 50 mm. Theremainder is slabwood waste which is either chipped or used as fuel. Theflitches 42, 44 and 46 in FIG. 2 are all quarter sawn sliced wood asreferred to in FIG. 1 which are advanced for slicing at position 10.

This method of log breakdown provides for the cutting of pinus radiatasoftwood logs by targeting the clearwood at the base of the log,achieved by log pruning regime, so as to utilise by this process 2 to 6metre log lengths to achieve maximum wood utilisation and quality. Theprocess also provides for the modification and upgrading of the corewood so as to integrate this material as suitable substrate for themodified high value outer wood panel claddings, and also to laminate themodified corewood into structural products. Alternatively, otherfibreboard options or other suitable material (metal or synthetic) maybe used as substrates.

Two alternative optional steps which assist in the preparation of woodfor subsequent processing may be carried out as illustrated in stages 9Aor 9B. In stage 9A hardwood flitches or slabs may be soaked in hotwater, “ponding”, or steam to soften the wood. Alternatively the flitchsurface in stage 9B maybe heated by using infrared radiation.

This wood heating step further breaks down the residual wood fibre toassist in maximum penetration of the fatty acid compounds in both theheated bath and/or the vacuum pressure chemical impregnation step 21.

These steps help achieve fixation of the wood fibre cell structure andalso provide increased dimensional stability. The modified wood issuitable for subsequent applications of adhesives and also UV pigmentedclear surface coatings designed to block UV radiation. The processdesigned to lessen the breakdown of the wood surface. The compressedwood has increased strength somewhat in proportion to the compression,and greater than that when the modified wood is laminated into layers.

In one alternative a log is sawn in flitches, which are then eithermulti-blade sawn or sliced at sawing/slicing stations 10 or 19. Inanother alternative selected width slabwood piece from the sawn log isre-sawn at the sawing station 11.

An alternative hardwood sawing method comprises the reduction of a logto short lengths, eg 2-3 metre log lengths using a log “centre drive”horizontal log band saw. Such a saw has an automatic adjustment of theheight of log table to provide for continuous thin cutting sequence andautomatic log turning to cut to a specific thickness range. Thesubsequent cuts from this step are to width by a multi-saw at station12.

The various cuts are then stacked at station 13A and conveyed to thenext stage.

Wood Drying

The slices of wood are then optionally dried. In a preferred embodimentthe drying is conducted in vacuum driers 14A or 14B where the drying maybe assisted by use of superheated steam in conjunction with a vacuum.

The preferred method of pre-drying the softwood is to dry of both thewood flitches and edged slabwood in a vacuum dryer with fans, and withthe wood placed in layers between wood or plastic fillets. This done atstation 14A.

The preferred method for pre-drying diffuse porous hardwood is in avacuum/pressure dryer with heated plates between each wood layer, andwith constant top pressure to accommodate the wood shrinkage duringdrying. This is done at station 14B.

The sawn wood strips and the re-sawn lumber may be dried to thepreferred moisture content range of approximately 40-50% (W/W) fordiffuse porous hardwood, and 30-40% (W/W) for softwood.

In station 14A, which has a vacuum drier with fans, layers of wood areseparated by wooden or plastic fillets to encourage the movement of thesuper heated steam through the layers of timber. This movement providesadvantages in the drying of softwood (such as pinus radiata) andespecially for large flitch sizes. Tis method may be preferred where themultiple slice/sawing option 15 takes place after this drying process.The moisture content of pinus radiata which is normally in excess of140-150% (W/W) is reduced in this pre-dry step to approximately 35-40%(W/W) in readiness for the next sawing and compression stages.

A vacuum press/dryer suitable for carrying out a pre-drying step instation 14B is a square section vacuum drying oven which is operated ata temperature up to normally 80-90° C., and with vacuum of approximately150-200 Mbar absolute pressure in the dryer. As a result of the vacuum,moisture is removed from the wood from the centre outwards (opposite toconventional drying). The water evaporates and becomes super heatedsteam, which, because the drying is in an oxygen free atmosphere,ensures the wood remains a light colour.

During this pre-drying step it is preferable to apply a constant toppressure to the wood layers. In addition, heated plates are providedbetween each layer to keep the wood flat and straight. A preferredpressure of up to 10,000 kg per sq. mtr. of wood surface to helpcompensate for wood shrinkage. This pressure also assists in avoidingcellular collapse during this first stage drying on hardwoods prior tothe first compression step 17.

The steam created during this step between the heated plates and theheated lumber keeps the wood surface wet during the drying process. Thecomputer control settings are adjusted according to the wood species toobtain accurate moisture settings. When diffuse porous hardwood ispre-dried the moisture content is reduced preferably to 40-50% (W/W) inreadiness for the next compression stage.

Both the vacuum/pressure drying at station 14B and the vacuum dryingwith fans at station 14A cause evaporation of turpentine in the woodresins. A small portion of chemical extracts, such as beta pinene, maybe separated at the outfall of the dryer. The resins come to the surfaceof the wood as a friable sugary substance, which is easily removed. Thisdrying method gives an even light surface colour to the product and alsoprovides good adhesion for subsequent lamination. It also allows foreven coverage of surface coatings on the products of this invention.

Alternative Sawing Step

At station 15 softwood flitches may be cut into slices (such as slices42, 44 and 46 in FIG. 2) after the drying stage 14A. This is analternative to the operation at step 10 described above.

Where the flitches are from logs with knots (such as pinus radiata) theyare also cross-cut and end jointed to predetermined lengths. These arethen combined with flitches of the desired length for later stages ofthe processing.

At stage 16 the pieces cut to length at stage 15 are lifted in layers byan overhead gantry and advanced to the first compression stage 17. Thegantry is preferably equipped with a vacuum clamping mechanism known inthe art.

First Compressive Deformation

After the initial partial drying of the wood, at stations 14A or 14Bdepending on the wood species, the wood is subjected to compression atstation 17. For diffuse porous hardwood lumber with a pre-compressionmoisture content of 35-45% (W/W) the compression will be in the range of25 to 40% of the starting wood thickness.

For compression of partially dried softwoods with a pre-compressionmoisture content of 40% (W/W), less compression will be used, so as notto close the wood cells completely, and for such wood a compressionfactor of approximately 20-30% will be used.

The pressure and heat required for such compression is based on thefollowing:

Thin wood strips or blocks are conveyed at up to 40 mpm, between twoheated platens of 250 mm thickness used for both strength and accurateheat dispersal. Either hot oil or steam may be used as a heating medium.The temperature is maintained at a preferred range of up to 180° forsoftwoods, and up to 200° C. for the hardwoods. A special steel conveyormay be used at the higher pressure.

In another embodiment for the compression of softwood with knots in thewood strips a replaceable compression mat would be used. The mat issuitable for both heat transference, and with sufficient elasticity ofthe surface for the variable positioned knots (normally harder than thesurrounding wood), to be compressed into.

The compressive forces suitable for hardwood compression will be up toapproximately 96 kg/cm² and for softwoods a pressure up to 60 kg/cm².The plates are hydraulically actuated.

A compression apparatus machine suitable for use at station 17 isequipped with a shake function for ease of wood removal after thecompression process, and to provide for automatic out feeding from theheated plates. The machine is provided with a multistage compressiondevice to avoid blow outs of the wood during the compression process.The machine includes spacing bars to be set for the variable woodthicknesses as required. The machine is also controlled by computeriseddepth settings which can be programmed according to wood species andmoisture content.

The compressive process on hardwoods can take place either from “greensawn” (wood processed directly after log sawing) or after the preyingprocess at stations 14A or 14B. In both cases sufficient pressure andheat are used to bring the moisture content down to approximately 4-6%(W/W) prior to the next stages of the process.

Once the wood strips are removed from the compressive deformationchamber, owing to the heat and pressure, the wood is in amalleable-softened state. If knotty wood is compressed it is subjectedto a surfacing/calibrating process prior to the next stage.

Bound water in the convoluted cellular structure of difficult to drytimbers, such as the New Zealand nothofagus beech species and fastgrowing eucalypt hardwoods is removed by this step. Both types of woodare prone to cellular collapse during conventional drying processes.

In another embodiment there is provided a pre-compression stage (13B),using a set of stainless steel heated conveyor pressure rollers whichapply constant pressure up to 40 kg/cm² or as specified according to thewood species. This preliminary step releases the wood tension from theconvoluted cell structures prior to the hardwood vacuum/pressure drying,14B. This energy release is applicable to timbers which have a tendencytowards cellular collapse during normal wood drying processes. Also,after the flitch-softwood drying, for additional removal of wood resins,this roller pressure option is available. The heated rollers may be upto 500 mm in diameter and comprise 2 or 4 sets of counter rotatingrollers with either knurled or grooved surface to facilitate removal ofthe moisture during this initial compression step.

At stage 18 the lengths of wood from first compression stage 17 are, inone embodiment, end jointed to one another. The preferred method isfinger jointing. The joints are glued, clamped and cured. The joinedlengths are then planed.

At stage 19 the extended length flitches from stage 18 are sliced orsawn lengthwise to the desired thickness. This may be done using amulti-bladed saw for convenience. This option is most advantageouslydone with softwoods. For high density hardwoods the multi-sawing ispreferably done at stage 10.

Hardwood from first compression stage 17 is preferably fed directly fromstage 17 to the impregnation stage 21. Softwood is preferably subjectedto stages 18 to 20 before being advanced to impregnation stage 21.

Chemical/Diffusion/Impregnation

The compressed wood from stage 17 is loaded either manually orautomatically into a heated bath of fatty acids, preferably in aparaffin carrier in stage 21. The bath or tank is preferably heated to atemperature of from 60° C. to 120° C. Preferred fatty acids are stearicor palmitic acids, but other fatty acids may be used. The fatty acidsprovide increased wood hardness and water repellency. Optionally astaining agent may be added to produce wood colour variation, such asteak, mahogany etc in the product. Wood preservatives and other chemicaladditives may be included in the bath 21. Preferably the bath chamber issubject to a vacuum pressure.

Second Compressive/Densification Step

Impregnated compressed wood strips are removed from stage 21, and areconveyed via link 22 on multi-rollers into heated compression plates atsecond compression stage 23. The plates have a high pressure liquidinjection system for additional supply of chemicals. Downstream of thepressure plates are high density spiral rubber (90 Shore hardness)pressure rollers. These rollers serve to squeeze excess chemicals fromthe wood. A chemical recovery bath is provided below the rollers toallow for continuous processing.

The wood is subjected to pressure within a range of approximately 20-30kg/cm² at a temperature ranging between 60-120°. This is the secondcompressive process, during which both densification pressure plates andchemical spreader rollers are employed to achieve mechanical pressurisedchemical impregnation to consolidate the chemicals into the wood as acontinuation of the impregnation step 21. This step is continued for upto about 6 minutes.

The product is conveyed via link 24 from the second compression stage 23to annealing stage 25.

The second compression step is used for softwood and up to mediumdensity hardwoods. It is optional for hardwood.

Moulding

In an alternative embodiment the second compression step formers can beused to mould compressed wood strips into desired shapes in top andbottom heated moulds (male and female jigs). The moulds are preferablyeither electrically or hot water heated but may be heated with otherheating media for the forming process.

The process can take place either before or after the annealing andcuring step 25. Adhesive may optionally be applied to the wood surfacesto enable bonding to take place in the formed product as a result of thecompression process.

Within the same step, and prior to the compression, the edges of thewood strips may be straightened and taped together in readiness of theforming/compression step.

Following the chemical/fatty acid impregnation of the pre-modified woodstrips, additional surface chemical applications are targeted to providewater resistance. The moulded products may be in the shape of plates,bowls or other similar articles. In other applications the moulds areshaped as furniture pieces.

Annealing

In stage 25 the compressed wood is dried in a continuous feed forced airor infrared drying oven. Wood strips are placed on trays which are fedby a conveyor vertically through an oven. During this stage thecompressed wood is annealed into a permanently compressed product. Thestrips are stacked once discharged and held for sufficient time for thefinal curing.

Final Compression

The annealed products are passed through link 26 to stage 27 where acold pack press is used to ensure the wood is held in an ordered stackin preparation for subsequent processing. The layers of the compressedmodified wood are interleaved with release layers, such as wax paper,between each layer of the wood, thereby preventing any surplus chemicalresidue from spreading between layers. Layer upon layer of thecompressed/modified wood are stacked for transport by using bottom andtop boards to cover the total stack length and width (which could be 6metres length×1.2 metres width), and with a pack thickness of as much as1.2 metres. The top and bottom wood panels are clamped together bymechanical locking clamps, with compression bars across the wood surfaceso that when the press is opened, the pack is rolled out of the press inreadiness for a further load. The packs are preferably kept under theseclamps for a period of up to approximately 12 hours.

They are conveyed by link conveyor 28 to the inspection and qualitycontrol stage 29.

Quality Control

In quality control stage 29 manual inspection of the modified woodstrips takes place, and defects are either patched, or the work piecesare cut to lengths not containing the defects.

Further Processing

The product is then conveyed via conveyor 30 from the quality controlsection to the further processing section 31. Here it is sanded on bothsides and calibrated to uniform thickness. It is then end and edgestraightened and trimmed and then formed into laminated products such aspanels and structural products. At link 32 the products are moved intothe UV Coating process, plus packaging of the finished products, stage33.

Wood which has been compressed by the process according to thisinvention is able to retain its compressed configuration so as to takepermanent advantage of its new wood strength, hardness, antiabrasiveness and dimensional stability.

REFERENCE

Inoue et.al., “Permanent Fixation of Compression Deformation of Wood.(II) Mechanisms of Permanent Fixation”, Presented at Conference:Chemical Modification of Lignocelluloses, 7-8 Nov. 1992, Rotorua, NewZealand

1-38. (canceled)
 39. A method of forming a compressed wood product comprising the steps of: subjecting a piece or pieces of softwood, with a moisture content of approximately 30-40% (w/w) to a first heating compression step in which the density of the softwood is increased to a first predetermined level and the moisture content is reduced to between approximately 3-8% (w/w), releasing said wood from said first compression step, coating and impregnating said compressed wood with a fatty acid, subjecting said impregnated compressed wood to a second heating compression step in which the density of said compressed wood is increased to a second predetermined level and the moisture content is further reduced and in which said fatty acid is further impregnated into said compressed wood, and releasing said wood from said second compression step and allowing said impregnated compressed wood to anneal while cooling to ambient temperature.
 40. The method as claimed in claim 39, wherein said softwood is subjected to a preliminary drying step prior to said first compression step.
 41. The method as claimed in claim 39, wherein said first compression step is conducted at a pressure of from 50 to 114 kg/cm² according to wood species.
 42. The method as claimed in claim 39, wherein the temperature of said first compression step is within the range of 140° C. to 185° C.
 43. The method as claimed in claim 39, wherein said softwood is subjected to a temperature of up to 200° C. prior to said first compression step.
 44. The method as claimed in claim 39, wherein said compressed wood is impregnated by passing it through a heated bath only, or in combination with a vacuum pressure chamber.
 45. The method as claimed in claim 44, wherein said fatty acid is in a paraffin carrier.
 46. The method as claimed in claim 39, wherein said fatty acid is a member of the group consisting of stearic acid, palmitic acid and a combination thereof.
 47. The method as claimed in claim 39, wherein said second compression step is conducted at a temperature between 60° C. and 140° C.
 48. The method as claimed in claim 39, wherein said wood is subjected to a preliminary drying step to reduce its moisture content before said first compression step.
 49. The method as claimed in claim 48, wherein said wood is subjected to an intermediate step of immersion in hot water or superheated steam between said preliminary drying step and said first compression step.
 50. The method as claimed in claim 39, wherein said compressed wood from the said second compression step is subjected to further processing.
 51. A method of forming a compressed wood product comprising the steps of: subjecting a piece or pieces of diffuse porous hardwood, with a moisture content of approximately 40-50% (w/w) to a first heating compression step in which the density of the hardwood is increased to a first predetermined level and the moisture content is reduced to approximately 4-8% (w/w), releasing wood from said first compression step and coating and impregnating said compressing wood with a fatty acid, optionally, when said wood is hardwood, subjecting said impregnating compressed wood to a second heated compression step in which the density of said compressed wood is increased to a second predetermined level and the moisture content is reduced to suit end product requirements, at as low as 2-4% (w/w) and in which said fatty acid is further impregnated into said compressed wood, and releasing said wood from said second compression step and allowing said impregnated compressed wood to anneal while cooling to ambient temperature.
 52. The method as claimed in claim 51, wherein said hardwood is subjected to a preliminary drying step prior to said first compression step.
 53. The method as claimed in claim 51, wherein said first compression step is conducted at a pressure of from 50 to 114 kg/cm² according to wood species.
 54. The method as claimed in claim 51, wherein the temperature of said first compression step is within the range of 140° C. to 185° C.
 55. The method as claimed in claim 51, wherein said softwood is subjected to a temperature of up to 200° C. prior to said first compression step.
 56. The method as claimed in claim 51, wherein said compressed wood is impregnated by passing it through a heated bath only, or in combination with a vacuum pressure chamber.
 57. The method as claimed in claim 56, wherein said fatty acid is in a paraffin carrier.
 58. The method as claimed in claim 51, wherein said fatty acid is a member of the group consisting of stearic acid, palmitic acid and a combination thereof.
 59. The method as claimed in claim 51, wherein said second compression step is conducted at a temperature between 60° C. and 140° C.
 60. The method as claimed in claim 52 wherein said wood is subjected to a preliminary drying step to reduce its moisture content prior to steam heating and before said first compression step.
 61. The method as claimed in claim 60, wherein said wood is subjected to an intermediate step of immersion in hot water or superheated steam.
 62. The method as claimed in claim 52, wherein said compressed wood from the said second compression step is subjected to further processing. 